1. Field
The following description relates to a terminal that is used in an Orthogonal Frequency Division Multiplexing (OFDM) system, and an apparatus and a method for minimizing the number of input bits of a Fast Fourier Transformer (FFT) in performing a fast fourier transformation at a receiving end of a OFDM based Wibro terminal.
2. Description of the Related Art
When a received symbol is modulated in an Orthogonal Frequency Division Multiplexing (OFDM) system, the modulation is performed using Fast Fourier Transform (FFT). Since a FFT engine is highly regarded in implementing the overall OFDM system, many studies have been undertaken to enhance the implementation efficiency of the FFT engine.
Various methods have been proposed to effective implement the inner logic of the FFT engine. According to a technology related to the input bits providing the optimum performance of the FFT, at least 6 bits of input bits are required to obtain Signal to Noise Ratio (SNR) loss of 0.1 dB or below, that is, 6 bits are the minimum number of input bits without affecting the FFT performance.
The FFT engine is highly regarded in implementing the overall OFDM system. Accordingly, as the number of input bits of the FFT engine increases, the complexity of the interior design of the FFT engine is significantly increased.
Accordingly, there is a need to obtain the performance in Bit Error Rate (BER) in a wireless communication using OFDM and determine the minimum FFT input bit that produces a SNR difference of 0.1 dB or below with respect to a theoretical graph at a desired performance. In addition, there is a need to know the change of the minimum input bit of the FFT engine according to the modulation scheme and adaptively determine the number of the FFT input bits.